Method of and machine for grinding rotary cutters



April 23, 1929.- 1,710,533

METHOD OF AND MACHINE FOR GRINDING ROTARY CUTTERS G. A.- DE vuse Filed May 15,

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Filed May 15, 1926 11 Sheets-Sheet 4 INVENTOR N EEJ'H'DflDEME NBY ATTORNEYS 23, 1929- G. AL/DE VLIEG METHOD OF AND MACHINE FOR GRINDING ROTARY CUTTERS ll Sheets-Sheet Filed May 15, 1926 1. Mag 6.

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METHOD OF AND MACHINE FOR GRINDING ROTARY CUT' I'ERS G. A. DE VLIEG .11 Sheets-She et 9 Filed May 15, 1926 E FOR GRINDING ROTARY CUTTERS l1 Sheets-Sheet 10 April 23, 1929. (5., A. DE VLIEG METHOD OF AND mcnm Filed may 15, 1926 INVENTOR ATTORNEYS April 23, 1929. 1,110,533

OR GRINDING ROTARY CUTTERS I e. A. DE VLIEG METHOD OF AND MACHINE F Filed May 15-, 1926 11 Sheets-Sheet J.1-

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ATTORNEYS novel method of and machine for grinding Patented Apr. 23, 1929.

UNITED STATES PATENT OFFICE.

GERARD A. DE VL1EG,OF ROCKFORD, ILLINOIS.

METHOD on Am) MACHINE FOR GRINDING ROTARY our'rnns.

' Application filed my 15,

rotary cutters of'the reamer type.

The present application is a continuation 1n part of my application Serial No. 7 56,418 filed December 17, 1924. The primary object of the invention is to provide a new and improved method of and machine for grinding and relieving reamers having helical or inclined cutting edges lying in a cylindrical area.

A more specific object is to provide a reamers having helical cutting edges by means of which reamers may be provided that will not chatter when in use.

Heretofore reamers have first been ground cylindrically round, and have then been relieved, to provide clearance by cutting away the back of each blade up 'edge. This overhang has a cylindrical surface spaced equally with the cutting edge from the axis of the reamer, an d at the nose which doesmost of the cutting results in the formation of minute "waves in the surface of the bore being reamed, and hence in chattering' To minimize this chattering,

the cutting edges have commonly beeh unevenly. spaced about the reamer. v

The present invention contemplates i grinding the reamer to the desired. size by cutting a-ininute angle at each" cutting edge to provide-a cutting clearance, thereby substantially" eliminating any radial land or overhang; and grinding a'second angle on theback of each blade to. provide a relief clearance.- The present method therefore permits the cutting edges to be evenly spaced I about the reamer without causing chattering when in use, thereby maklng 1t I possible to flute solid tooth reamers by a generating process,such.as hobbing, and to rotatethe' reamer continuously in one direction during the grinding operation.

Another object of theinvention is to provide a new aild im roved method for grinding reamers where by aQsmooth finish is obtained on the nose, so-as to prevent the likelihood of 'thenose tearing the work in. the reaming operation. This object is accomv The present invention relates to an 1 m-, proved method of and machine for grlndlng toa narrow strip of land, or overhang next to the cutting 1926. Serial N0. 109, 222.

plished by passin the nose or ide an le of each blade ir iwardly over suitalily curved surface formed at one edge of an annular grinding face to first grind and then apply a drag on successive points along said nose. This drag is a very light touching of successive points along the nose by a portion of the receding curved grinding surface after said points have passed the effective grinding area of the grinding face, and serves to {produce a very smooth cntting edge.

Heretofore. reamers have been provided with a large single guide angl which in passing through-the bore being reamed had to remove ,the excess stock by a concen trated shearing action, thereby frequently tearing or producing rough spots .1n the work surface.

tion therefore is to, provide a novel method for grinding reamers whereby a plurality of adjoining end bevels are grou'nd'on the nose of each blade, one or more of said bevels constituting preparatory angles for removing most 0 reaming operation, and one bevel merging An important object of the present inventhe excess stdck in the.

at a small angle into the crown of the blade.

and serving to make the finish out.

A further object of the invention resides in the provision of a newand improved a inding face between the axes cause of the innercurvature ofthe grinding face.

An important object of the invention resides in the provision of a novel method of and machine for grindin reamers wherein the reamer is rotated continuously in one direction to compensate for the inclination of the blades and to position successiveblades in the grinding stroke, thereby obtaining .65 23, 24 and 25 are similar .d1-agram-' accuracy, speed, uniformity, even cutting clearances, and alignment of i the 'nose angles. I

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawings, Figure 1 is a fragmentary front elevation, partially in section, ofa grinding machine for carrying out my invention.

Fig.2 is a plan view of the grindmgmachine. I I Fig. 3 is a-transve'rse section of the grinding machine taken substantially along line 3-3 of Fig. 2. Fig. 4 1s a. longitudinal section of the grinding machine taken substantially. along along line 7-7 of Fig. 2, and showing thedriving connection between the work carriage and the reclprocating mechanis therefor.

Fig. 8 is a fragmentary perspective view' of the head-stock with the clearance setting mechanism.

Fig. 9 is a detail sectional view of the adjusting cam of the clearance setting mechanism.

Fig. 10 is a detail view of the clearance setting mechanism. showing the cam and Figs. 18 and re vdog in position to produce the maximum relief clearance.

Fig. 11 is a vertical section of the oscillating mechanism for the work carriage taken substantially along line 11-11 of Fig. 2. Fig. 12 is a fragmentary vertical section similar to Fig. 11 taken along line 1212 of Fig. 2.

Fig. 13 is a vertical section taken along line 13-13 of Fig. 11.

Fig. 14 is a vertical section taken along line 14-14 of Fig. 11.

Fig. 15 is a fragmentary horizontal section of the oscillating mechanism for the work carriage. Figs. 16 and 17 are diagrammatic views illustrating different stages in one cycle of the grinding operation for a left hand rotar-y cutter.

19 are views corresponding spectivelyto views 16 and 17 for a right hand rotary cutter. Figs. 20, 21 and 22 are similar diagrammatic views showing respectively the positions of the cutter relative to the grinding wheel when the first, the second, and the third of three nose angles are about to be matic views showing respectively .the specific relation of the shaped grinding face to each of the nose angles throu' h which the drag on the angle surfaces is o tained.

Fig. 26 is a side view of a blade formed with a plurality of nose angles.

Fig. 27 is a fragmentary view showing a I cutting edge formed with a single nose angle.

Fig. 28 is a diagrammatic view looking into the grinding wheel, and showing a blade in position across one side thereof.

Fi 29 is afr'agmentary enlarged view of Fig. 18 showing how added clearance is provided on the nose angle or angles. by movement over theinner edge of the grindingwheel. J a

= ig. 30 is a fragmentary sectional view showing the-relief generated on the crown of each'blade due to the angular position to which the cutter is set about its axis at the beginning of the operation.

Fig. 31 is a fragmentary end view of the cutter showing the relief on the crown of one blade and the relief on the nose.

Fig. 32 is a diagrammatic end view showing a left hand cutter in position for the grinding cut.

Fig. 33 s a VIGW' similar to 32 showing the position of saidcutter at the completion of the grinding cut.

Fig.- 34' is a diagrammatic view showing the position of adjustment ofthe clearance setting mebhanism to provide the cutting clearance.

' Fig. 35 is a-diagrammatic' view showing the position of adjustmentof the clearance setting mechanism to provide the maximum relief clearance. 7

Fig. 36 is anend view of a blade provided with a cutting clearance and a single relief clearance. f

Fig. 37 is a'view similar to Fig. 36 showing two relief clearances. I

While the invention is susceptible of various modifications, I have shownin the drawing and will herein describe in considerable detail the preferred. embodiment thereof, but it is to be understood that I do not therebyintend to limit the invention, but aim on the'contrary to cover all -modificathe a pended claims.

.tions falling within the spirit and scope of Re erring to the exemplary embodiment v -spindle mounting 39 and a work ca rriage 40.

The grinding spindle mounting (see Figs. 2 and 3) in the present instance comprises machine bed 38, and formed with a tubular housing 42 which extends substantially transversely of' the bed. A long. sleeve 43 is slidably mounted in the housing, and is -a standard 41 mounted on the rear of the held against rotation by a key 44. Journaled in the sleeve 43 and longitudinally movable therewith is a rotary spindle 45, the front end of which is provided with a grinding wheel G of suitable form and the rear end of which .is splined to a pulley 46 rotatably mounted in bearings 47 in the rear end of the housing 42. Thesleeve 43 is formed on one sidewith longitudinally disposed rack teeth 48 in mesh with a pinion 49 on a vertical stub shaft 50. The latter is geared through a worm gear 51 and worm 52 in a gear housing 53 on the standard 41 to a shaft 54 having a hand wheel 55, thereby providing means for adjusting the grinding wheel axially to compensate for wear or for variations in size. Mounted on the front end of the sleeve 43 for movement therewit'h is a dust guard in the form of a cylindrical housing 56 which telescopes with the front end of the housing 42. A hood 57 for the grinding ,wheel G telescopes with the front end of the housing 56, and can be adjusted by'ineans of a non-rotatable screw 58 extending rearwardly through two spaced lugs 59 on the housing, and carrying an adjusting nut 60 between said lugs.

The cutting face of the grinding wheel G may beformed with the desired shape in housed in the bracket 61, and mounted on a shaft 67 having an operating handle 68.

Extending through the inner sleeve 64 and pivoted centrally therein for movement late'rally of the grinding face is a tool holder 69, the outer end of which carries a cutting tool 70, and the inner end of which is pro-, vided with a pin 71. The latter extends outwardly through suitable openings in the sleeves 68 and 64, and'is pressed against a cam 72 by a coil spring 73 engaging the remote sideof the holder The cam 72 has a shape such that in moving the dressing tool over the grinding wheel G by actuating the handle 68,the desired contour Will be cut on the grinding face.

To drive the grinding spindle 45. the pulley 46 is connected through a belt 74 to a pulley 75 which is formed integralwith a clut-ch member 76 suitably supported in a bearing bracket 77 on the rear side of the. machine base. Extending slidabfy'but nonrotatably through the clutch member 76 is a drive shaft 78 on the rear end of which i a pulley 79 is rotatably mounted. This pu'lley is adapted to be driven by a belt 80 de-.

riving power from any suitable source, and is formed with an'annular clutch flange 81 movable upon reciprocationof the shaft 7 8 into or out of frictional engagement with the clutch member 76. A heavy coil spring 82 disposed between a collar 83 on the shaft 78 and a sleeve 84 on-the clutch member 76 tends to move the shaft and pulley for.

of the shaft 78 is slidably and rotatably' supported in bearings 86 which are mounted in a tubular sleeve 87 on an inwardly extending bracket 88 formed on a front plate 89 ofthe base. Rearward movement of the shaft 78 tothrow oil the power can be effected by means of a screw 90 which is threaded through a cap 91 in the front end. of the sleeve 87 into engagement with the front end of the shaft, and which is adapted to be actuated by a suitable hand lever 92.

The work carriage 40. comprises ,a long narrow slide or sub-base 93., (see Figs. 1 to 4), which is mounted for longitudinal reciprocation on ways 94 on the bed 38, and a table '95 which is mounted on said subbase for pivotal movement about a stud 96 at its left end. Ball bearings 97 mounted in complementary grooves 98 in the sub-base and the table serve to facilitate this movement. The free end of the table 95 is pro vided with a reduced extension 99 which is movable between twospaced blocks 100 on the. sub-base 93, and which is pressed rearwardly by a coil spring 101 mounted in the front block. Rearward movement of the extension 99 can be prevented or limited to the desired extent by means of a hand screw 102 threaded through the rear block 100 and having a lock nut 103. A plate 104 secured to the blocks 100 slidably engages the upper surface of the extension 99, and.

thereby serves to hold the table 95 against vertical displacement on the sub-base 93.

Adjustably mounted on the right and left ends respectively oft-he table 95 are a tailstock 105 and a headstock 106 having op posed centers 107 and 108 respectively between which a suitable work arbor 109 is rotatably mounted. The axis of the arbor 10.9 is located in a plane below that-of the grinding spindle axis for a purpose hereinafter set forth. In the present instance, each stock is formed with'a guideway 110 'and provided with a gib 111 (see Fig. 3)

respectively engaging and adapted to be clamped against tvi'o longitudinal dove tailed guides 112 formed in theside edges of the. table 95. Each gib 111 is supported by a clamp screw 113 extending through the body of the stock.

The center-107 of the tails'to'ck 105 is 1ongitudinally adjustable in the latter, and can be clamped in position bymeans of a set screw 114. I

The arbor.109 is adapted to support any one of large variety of cutters or blade holders, and is herein shown supporting a rotary cutter C having inclined or helical blades 0. The method is'applicable to cut-- tors having solid or inserted blades. ,The blades of the cutteiwmay have a single nose or guideangle a as shown in Fig.27, or a plurality of adjoining nose angles, such as angles a','a", and a-' shown Fig. 26. I

The. housing of the headstock 106' is formed on its left ,end'wall, as viewedv in Fig. 4, with an inwardly extending core 115 having a central bore 116. Mounted in the bore 116 is a socket member 117'having a tapered bore 118 in which the work center 108 is seated. Rotatably mounted on the core 115 is a gear 119 having an annularfiange 120 on one side concentric with thecenter 108 and projecting out from the right end of the housing. To prevent back lash in the gearing, a spring pressed brake shoe 121 is mounted in the housing in engagement with the hub of the gear 119. The right end of the housing is closed by two annular wall members 122 and 123 secured respectively to the. free end of the core 115 and, to the housing, and

- cam surfaces 6, b, b", and b'"- end of the drive sleeve 129 is formed with tions.

engaging the inner and outer peripheral surfaces of the flange 120.

Rotatably mounted on a screw bolt 124 (see Figs. 8 and 9) threaded into the end of the flange 120 is a cam member 125 having its inner end' a peripheral shoulder 126 on bearing against said flange. The cam menu ber 125 (see Figs. 8,10, 34 and 35) is formed with a plurality of distinct 'arcuate'surfaces, four surfaces b, b, b", and 6 in the present instance, which are located respectively at progressively greater distances from the center. A plurality of radial notches 127 (see Fig. 9) are formed in the inner face of the shoulder 125,, and areadapted to be selectively engaged by a spring pressed plunger 128in the flange 120 to hold the cam member 125 yieldingly in any one of its four posi- Mounted rotatably on the center 108, and extending into the wall member 123 is a drive sleeve 129 having a peripheral flange 130 intermediate its ends. A" ring 131 is. i'otatably mounted on the sleeve 129, and

' may be adjustably secured against the inner side of-the flange 130 by means of a pair of clamp screws 132 threaded into the ring and extendingthrough arcuate slots 133 in the flange. The ring 131 is provided-with a dog 134 which projects into the path of the cam member, 125 to engage any one of the The outer a key 135 adapted to interlock witn a similar key 136 on a dog 137 secured to the arthe shank of bor 109. It will be evident that the'cam member 125 and the dog 134 constitute an adjustable'means in the drivin connection between whereby the arbor with the cutter C can be the arbor 109 and t e gear 119 relatively adjusted into different angular positions about their comriion axis. I

To initially locate thecutter blades 0 with respect to the grinding wheel G, the surface I) is brought into engagement with the dog 134. and the sleeve 129 is adjusted relative to the ring 1 30. The correct ppsiti'on is determined by means, of a gage (see Fig. 5) which comprises a finger 138 adapted to be moved from "an-{inoperative position into position next tidthe effective area of the grinding face. In the present instance, the

linger 138 is pivotally secured to the lower 1 adjustably disposed in a vertical bore 140 which extends through a tubular sleeve 141' sleeve 141 encircles the adjusting nut 144 and serves toindicate the position of ad end of a non-rotatable supporting bar 139- 140 is closed justment of the bar 139. To take up lost I motion, a coil spring 147 is positioned-onthe stem 143'between the bar 139 and the bushing. 142. The finger 138 is formed with by means of which it can be moved up wardly into inoperative position, (shown 1n a point 148 adapted to engage the tac'e of a. cutter blade 0, and with a finger grip 149 l outline). A

It will be evident that the gage is ened to clamp the dog 134 to the sleeve 129. 7

To slowl and continuously rotate the arbor 109 see Fig. 4), the gear 119 is in mesh with a. pinion 153 on'a shaft 154 which is adjustable with the headstock 106, and which extends slidably through a gear housing 155 mounted on the left end of the table ,95. The shaft 154 is connected through a train of change speed gears156 in the housing 155 to a stub shaft 157. By changing the intermediate gears 156 the speed cf the shaft 154 can be varied so as to conform to different numbers of blades.

cutters and reamers of different sizes and "of 162 in the bracket 88. A worm wheel 163 'on the shaft 161' meshes with a worm 164 splined to the drive shaft 78.

To reciprocate the carriage 40 in timed relation to the rotation of. the cutter .C, a

left hand cam 165 and a right hand cam 166 having cam grooves 167 and, 168 respec:

- tively are mounted on the shaft 161 at oppo- 168 respectively.

site sides of the worm wheel 163. Slidably mounted in a longitudinal guideway 169 in the lower surface of the subsbase 93 and held therein by a gib 170 are af pair of slides 171 and 172 having depending pins 173 and 174 engaging the grooves 167 and A pair of locking pins 175 and 176 are slidably mounted in the front edge of the sub-base 93, and are adapted to engage two depressions 177 and 178 in the slides 171 and 172 respectively to lock the latter selectively to the carriage 40. Each pinis provided with a shoulder 179 (see Fig. 7) slida. lei in a bushing 180, and is yieldingly pre sed inwardly by acoil spring'181. Pivotally mounted on the subbase between the pins 175 and176 is an.

interlocking lever 182, the opposite ends of which extend through notches 183 in the bushings 180 and are adapted to engage the shoulders 179 to hold the pins in their retracted positions. The" lever serves to prevent both slides 171 and 172 from being locked to the carriage at the same time.

The cam groove 167 (see development diagrams in Figs. 16 to 19) comprises sections (Z and 03 respectively, formed to give the carriage 40 a slow working movement to the left and a quick return movement ..to the right. Sections 6 and e of the cam groove 168 are adapted to effect a slow movement of the carriage to the right and a quick return to the left.

is designated as the grinding stroke, and the quick return movement as the return- For convenience the slow movement stroke.- The slope or pitch of the cam sections 0! and e is such that successive points along the cutting edge of the blade being ground are rotated into grinding position blades o of the cutter successively to the as they move across the effective cutting area of the grinding wheel G. To present the grinding'wheel G, the velocity ratio of the cam shaft 161 and the arbor L09 'is'made to equal the number of the blades, and n the present instance is therefore 6 :1. To insure accurate grinding, it 1s necessary that the cutter C be initially correctly positioned relative to the grinding wheel G and. the cam grooves Means is provided for effecting a relative.

The stub shaft "adapted to engage a cam .186 having a cam face, the right end of which is parallel to the sub-base 93, and the left end of which is in clined rearwardly. When single nose angles a are to be ground on the blades 0, a cam 186 with a single angle or bevel f on its left end, as shown in Figs. 2, 13 and 15, is provided. #When a plurality of nose angles 41), a, and a are to be ground on the blades 0, a cam 186 .with a plurality of angles or bevels f, f, and f on its left end, as shown in Figs. 16 to 22, is provided.

The cam 186 rests on the front end of a block 187 which is rigidly secured on a forwardly extending shelf 188 of a suitable housing or frame 189. The latter is adjustably mounted on a dove-tailed guide 190 extending laterally of the base 38 and rigidly secured-thereto by bolts 191. Formed integral with the frame 189 is a rearwardly extending shell 192 which fits slidably over the edges of a bracket 193 onthe rear end of the guide 190. A nonrotatable screw 194 is rigidly secured to the frame 189, and extends rearwardly into threaded engagement with a sleeve nut 195 rotatably mounted in a bearing 196 on the bracket 193. The nut 195 is provided with a hand wheel 197 for adjusting the frame 189 andhefice the cam 186 toward and from the table 95.

-The cam 186 is secured by means of bolts 198 to the underside of a'slide 199 resting on the block 187. The permit longitudinal adjustment of the cam 186, the slide 199 is formed with a guide way 200 engaging a dove-tailed guide. 201 on the block 187. A. guard plate 202 on the frame 189 projects over the slide 199 to prevent the entry of foreign matter between thebearing surfaces. An adjusting screw 203 rotatably mounted in a side bracket 204 on the frame 189 has 115 a threaded engagement with the slide 19$; and is provided with a suitable handwheel 205. The screw 203 is provided with amiturned to its original position out of contact 2 with the wheel. .It/is obvious that where the blades are sufiiciently Spaced, this result can be obtained by extending the reciprocation 5 beyond the ends ofthe cutter, and by causing the grinding wheel to pass between adjacent 139V blades on the return stroke. Preferably,

. however, the cutter and the grinding wheel are separated laterally during each return stroke. To this end, a left hand cam 207 and a right hand cam 208 are pivotally mounted in the left and right sides respectively of the block 187, and are adapted to selectively engage a cam roller 209 carried by the bracket 184 to oscillate the cutter O away from the grindin wheel G for the quick return movement 0% the carriage 40.. The cam face of each cam terminates next tothe pivot I in a circular recess 210 which is partially-defined by a forwardly extending arm 211.-

Each cam is pressed rearwardly from the roller 209 by a coil s ring 212 mounted between the arm 211 an the adjacent side wall of the frame 189, and is moved'forwardly when the roller engages the arm." 'A. pair of pawls 213 and 214 are pivotally mounted in opposite sides of the block 187, and are pressed toward each other by coil springs 215 to respectively engage the free ends of the cams207 and 208 as the latter are moved forward. Extending through opposite side. walls of the frame 189 are a pair of adjustable s'crews 216 adapted to engage the heels .of the pawls to hold the latter inoperative.

riage 40. The inner peripheral edge of the grinding face is formed or shaped as best shown in Figs. 23 to .25, to provide a contour which will cause a drag on'the ground surface of the cutter nose when the cutter is 1 caused to move inwardly This drag is a very li ht touching of the blade by the wheel of the grinding face recedes'inwardly along and'is or the purpose of producing a smooth edge thereon: Consequently the inner edge curved or substantially elliptical elements.

. When. grinding a cutter having a plurality of nose angles, different points 9, g", and 9 on the grinding face respectively apply a dra successively to the nose angles a, a;

and

'Themethod and operation will now be described. with reference first toa left hand I cutters havinga plural ty of nose angles.

cutter *andthen to a righthand cutter, both Initially, t e gears." 156 are changed, if

" necessary',fto correlate the translatory movement of the table .95 and the rotatory movef" and f' which will produce angles a, a

' of .the desired length and size.

ment of the cutter G to the angle of the blades'c.

A cam 186 must be used having angles f,

and a 4 While the angles a, a! and a' g r varied between certain hm1ts,prefera ly the angle a is between 30 and 1 30', say 45', the preparatory angle a is between2 and 3, say 215, and the guide angle a' which serves to center the cutter in the bore is abgut 15. The cam 186 is adjusted, if necessary, so that it will p rmit the inward movement of the cutter C at the, proper time. The: cam 165 is locked to the sub-' base 93, the carriage 40 is positioned to begin movement to the left so as to locate the cutter C in the rindin stroke, and the awl 214 for the might hand inoperative. The position of the in 173 in the groove 167 corresponding to t at of the carriage 40 is indicated in full lines in Fig. 16. The gage finger 138 is now oscillated into operative position to locate a point h (see Figs. 5 and 32 on the cutting face of the grinding wheel it slightly below the horizontal plane of the latter, and the cutter C isset to position the upper left end of the cutting face of one of the blades 0 against the lower end of the finger. With the cutter in this'position, the dog 134 of the clearance setting mechanism .is brought into engagement with the'cam surface I), and is then cam 166 is ren ered secured to the ring v130 by tighten-ingthe '4 bolts 132.

The axis of the arbor 109 is substantially below that'of the rinding wheel G and below the point h. he eifective grinding area substantially alon a c 0rd of the circle of rotation of the b ade edges being ground.

Each blade 0 will therefore be relieved, as illustrated in Figs. 30 and 31, along line falling well within the arc iu-j about the axis of the cutter C. This relief will be the cutting clearance o, illustrated in Figs. 34, 36 and. 37, for the cutting edge of each blade 0. y

I In the movement of the carriage 40 to th left, the cam arm 185 rides on the cam 186, and the cutter moves along line h-l to the dotted position shown in Fig. 16 to grind the crown of the blade,.the cutterbeing rotated in timed-relation to this movement to bring successive oints along the cutting of the wheel thus is located between the axes of the grindingspindle 45 and the arbor109. Hence the lane of said area is.

edge of the blade into engagemei'it with the cutting face at thepoint h. -The position of .the pin v173 in the, cam groovc at this stage is illustrated in dotted lines in Fig. 16.

Upon further movement of the carriage,'-

the cam arm .185 rides successively on the angles f, f", and f of the cam 186, and

thereby permits'the table to"be gradually eral formed surface of the grinding faceare tangential respectively to the nose angles a, a and a, and apply a drag to said angles after the latter have been round by their initial contact with the grin ing face. Since contact with the grinding face shifts, the junctions of the angles and of the angle a with the, crown of the blade are slightly rounded. The angles .a, a" and 0. are relieved along lines 1z 0, mfi-o', and n0" (see Fig. 31) which fall well within the arch-j about the aixis of the cutter. Since the point h is located slightly below the horizontal plane of the grinding wheel G, the angles a, a and a are given a greater relief than the crown of the blade. This is I due to the additional component of relief generated by the curvature of the formed inner edge of the grinding face, as illustrated in Figs. 29 and 31. The position of the cutter C. at the completion of the beveling cuts is the same as that of the cutter ingle nose angle a shown in Fig.

As the carriage s10 moves into its extreme left position, the roller 209 engages the'arm 211 of the cam'207, thereby moving the latter forwardly and permitting it to be engaged by the pawl 213. The pin 173.in the groove 167 and the cutter O assume positions shown in full lines in Fig. 17 In movement of the carriage 40 to the right, the roller 209 in leaving the recess 210 of the earn 207 oscillates' the table 95 forwardly beyond its central position, and then 'rides along the cam 207, thereby causing the cutter C to return along line mand line 12-17 out of engagement with t e grinding wheel Gr. As the carriage moves into its extreme right "position, in which the pin 173 and the cutter C assume positions -illustrate% in dotted outline in Fig. 17, the roller 209 disengages the pawl 213, thereby releasing the cam 207 and permitting the spring 101 to return all parts T to their initial positions; During the return -n'uovement of the carriage, the cutter C is rotatedto an extent such thatTin the next operationthe following blade is automatieally positioned in the grinding stroke.

' clearances.

vary with different cutters. Fig. 35 shows The cyclic movement of the carriage 40 is repeated until all the blades care ground to the desired size and with the desired clearances. When all the blades 0 have been ground with a cutting clearance c",.the dog 125 is adjusted to adjust the cutter C about its axis for grinding one or more relief The clearances to y be ground the dog 1 34 engaging the cam surface 6 tq position the cutter C for grinding a single maximum relief clearance 0'. The nose of a blade ground with clearances 0 and c" is shown in Fig. 36. By turning the cam surfaces'b and b selectively into position for engagement by the dog 134, intermediate relief clearances 0 and 0" may be ground. A blade ground with a cutting clearancev 0 and relief clearances c" and 0 ground *with the relief clearance 0' (not is shown 1n F1g..37.. Large cutters are pre erablyshown) as the maximum instead of the relief clearance c". In some instances, it may be desirable'to partially grind the .relief clearance before grinding the cutting clearance to the desired size.. 1

in grinding a right hancj ation is similar in princip e.

base 93, the cutter is set with the carriage in position to begin movement to the right, the

pawl 213 is rendered'inoperative, and the cam arm 186 is, resting on the inclined porti on of the cam 186. Movement ofthe carwage to the right results in moving the'cutter C first along brokenline rs to bevelthe end of the blade, and then along line st to grind the crown of the cutting edge (see Figs. 18 and 19). At the completion of the cut, the cam 208 is moved into and held in operative position, so that in the return cutter, the oper- Initially, the eam 166 is operatiwely connected to the sub- Rotating the cutter continuously in one direction in timed relation to the translatory movement causes successive points along each blade to be moved into engagement with, thegrinding face at thepoint' h during the cutting stroke, and causes the blades to be positioned consecutively in the grinding stroke in'suecessive cycles. By providing a cutting clearance, the cutting edge is ground to size. and relieved in a single machine oporation, and a radial land is substantially eliminated. Since the nose of the cutter has no radial land and since its angles have I greater clearances than -the crown of the blades, the cutter will not chatter when in use. By providing a plurality of 'nose angles, the desired diameter of the reamer is reached gradually. Each of the angles removes a small amount of metal, thereby tending to produce minute shavings. By applying a drag to these angles, the cutter nose is formedawitha' smooth accurate cutting .edge.

I claim as'my invention: i

1. The method of relief grinding the helicatory and'rotary motion between a bladeholder and a grinding wheel, and causing a relative approaching movement between said blade-holder and said wheel during an intermediate state of such combined reciprocatory and-rotary motion to grind a deflected end section on the blade.

2. The method of relief grinding the hellcal blades of cutting tools which comprises causing a combined or simultaneous reciprocatory and rotary motion between a bladeholder anda grinding wheel, and causing a series of relative approaching movements between said biade-holder and said wheel tion to saidcutter across a Ineht, which projects intozthe circle of rev'o- -lution of the cutter;-in timed relationto said during a predetermined stage of such combined-'-reciprocatory. and rotary motion to grind a-plurality of diiferently inclined contiguous nose angles on each blade, the first approaching movement being slight to cause the first nose angle ground'and adjoining the crown of theblade to be small.

The method of relief'grinding cutters having blades with, helical cutting edges which comprises i parting a continuous rotary motion to th cutter, a continuous'reciprocatory motion to said cutter across a grinding element, which projects into the circle of revolution of said cutter, in timed relation to said first mentioned motion, and

a relative' approaching movement between,

said cutter and said grinding wheel at a predeterminedpoint in said reciprocation; to grind a deflected section on each blade, said grinding element being removed from the surface being ground at appropriate times to pass from one blade to another.

at. The method of relief grinding cutters having helical cutting edges which comprises imparting a continuous rotary motion to the cutter, and a continuous reciprocatory morinding elefirst mentioned motion, said grinding element belng removed from the-surface being ground at appropriated times when pass- 7 ing from one edge to another edge.

5. The .method of relief grinding cutters having helical cutting .edges which com prises imparting a continuous rotary motion to the cutter, a continuous reciprocatory mo' 'tion to said cutter across a grinding element,

'which projects into the circle of revolution -.'of the cutter, at a ratio corresponding to the number of edges tobe ground so as to com pensate for the curvature of said edges and to move consecutive edges successively intoposition to be ground, and separating said grindingelement and said cutter laterally of said cutter during a predetermined stage of said reciprocatory motion to permit movement of said edges successively into grind-' 6. The method of relief grinding the blades of cutting tools which comprises positioning the blade to engage a grinding wheel between the axes of said grinding wheel and the $001 holder, imparting relative reciprocato y motion between said tool holder and said grinding wheel, and imparting a relative approaching movement between said too} holder and said wheel during a predetermined state of said reciprocatory 'motion to grind a deflected section on one end of said blade, the positioning of said blade serving to produce a relief on the blade and on the deflected section thereof. 1

7. The method of grinding the blades of so cutting tools, which comprises impart-ing a reciprocatory movement to ,a blade across a grinding wheel having an annular grinding face, the innerperipheral edge of which is formed to recede into the annulus of said 35 wheel and imparting a relative approaching movement between said blade and said face during a predetermined stage of said reciprocatory movement to move one end of said blade over said formed edge to grind and drag a deflected section of said blade.

8. The method of relief grinding cutting tools having blades with helical cutting edges,fiwhich comprises imparting a continuous rotary motion to the tool, imparting a relative 'reciprocatory movement between said tool and a grinding wheel having an annular face, said face projecting into the circle-of revolution of the tool, imparting a relative approaching movement during a predetermined stageof one stroke of each double reciprocation between said tool and 'said wheel to move the. nose of said tool parting a continuous rotary motion to the blade support, imparting a relative recip-' rocatory movement between said support and a grinding element, said rotary motion and said reeiprocatory .movement being timed tocompensate for the helix of each 1.

edge and to present-the blades successivelyto said grinding element during consecutive cutting strokes of said reciprocatorymove ment, and separating said support and said grinding element during the return strokes 12 of-{said reciprocatory movement. p

l0. The method of relief grinding cutters having. blades with helical cutting edges, wh ch comprises ,sitio ning the cutter so' thatj'each :blade will. element between the axes 'of said cutter and said element, feedings'aid grinding element 'into thecircle of revolution of said cutter, .impartijng a continuous, rotary motion to said cutter, imparting a relative reciprocontact with a grinding 2 catory movement between said} cutter and said element in such imed relation to said rotary motion so that the blades are presented successively to said element in con-.

secutive reciprocations, and imparting a relatlve approachlng movement at a predetermined point in each reciprocation between said cutter and said element to grind a deflected portion of each blade, said element being removed from the blades at appro-' 'priate times to permit passage from one between the axes of said cutter and said blade to another blade.

11. The method of grinding cutters having blades with helical cutting edges, which comprises positioning the cutter so that each blade will contact with v.a grinding element element, imparting a continuous rotary motion to said cutter, imparting a relative :reciprocatory movement between said cutter and said element. in such timed relation to said rotary motion that the blades are presented successively to said element in consecutive re'ciprocations, and adjusting said cutter about its aXis between reciprocations and after any complete rotation of said out-- ter to present different parts of the back of each blade to said element.

12. The method of relief grinding the helical blades of cutting tools which comprises causing a combined or simultaneous reci rocatory and rotary motion between a bla e holder and a grinding wheel, and causing a relative and 1 variable approaching movement between said blade holder and said wheel during a predetermined stage of such combined reciprocatory and rotary motion to grind a progressively increasing deflection on a section of the bla'de.'

13. The method of grinding the blades of' rotarycutt-ing tools which comprises posit'ioning the tool so that the blades will be presented successively to a grinding element at an angle tothe grinding face to grind one of two clearances, i. e., a cutting clearance to the desired diameter at the cutting edge, and a relief-clearance back of said cutting clearance, imparting a relative reciprocatory movement between said tool and said grinding element, and'adjusting said tool about its axis between reciprocations so that the blades will be resented successively to said element at a different angle to thegrinding faceto grind the other of said clearances.

14. The method of .relief grinding the blades of cutting tools comprising positioning the cutter to present a blade to a grinding wheel having an annular rinding face between the 'axes of said grindlng wheel and the blade support, with the face of the blade nearest the axis of said rinding wheel, relatively moving the blade ongitudinally across said face to grind the crown, and relatively moving the blade laterally during a predetermined stage of said first mentioned movement to pass the same over the inner pe-.

ripheral edge of said grindin wheel to grind a deflected end section 0 the blade, the curvature of said grinding face resulting in the grinding of a greater relief on said deflected end section than on the crown of the blade.

15. The methods of grinding the blades of rotary cutting tools which comprises positioning the tool to present a blade to the grinding element'between the axes of said tool and said element so as to grind a relief clearance on the back of the blades, imparting a relative reciprocatory movement between said tool and said grinding element,

and adjusting said tool about its axis beblade nearest the axis of said element, to I grind one of two clearances, i. e., a cutting clearance to the desired diameter at the cutting edge and a relief clearance back of the cutting clearance, imparting a relative reclprocatory and rotary movement between:

said tool and said grinding element, imparta ing a relative approaching movement be tween said cutter and said element to move one end of the blade over the inner peripheral edge of said grindi rig face during a predetermined stage of sa reciprocation so as to grind a deflected end sectipn on the blade, and adjusting said cutter about its axis between reciprocations, into another position to present the blade to said. element in a different osition between said axes to rind the ot er of said clearances, the pos tioning of the cutter relative to said grinding face for the grinding of said c1earances resulting inthe grinding of greater clearances on said deflected end section than on the crown of the blade.

17. A relief grinding machine having, in

combination, a grinding wheel, a support for a rotatable blade holder having a lade oblique to its axis of rotation,'means for rotating said blade holder, means for reciprocatingsaidgrinding wheel and said Y blade holder relatively to each other in a grinding stroke withqsaid wheel projecting into thecircle of revolution of said holder and in a return stroke, means for defining a line of grinding'contact conforming, in-

part, toan elongated blade crown, and a portion receding from such crown in the plane of theblade at one end thereof, and means for automatically separating said 

